Solve 7x − 2 = 138

The solution of 7x − 2 = 138 is x = 20.

7x - 2 = 138\ \Rightarrow\ x = 20

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The lines y = 7x − 2 and y = 138 meet at x = 20. The solution of the equation is the x-coordinate of the point where the two sides are equal.

How to work it out

1
The goal is to get x alone. Undo the operations in the opposite order: first the subtraction, then the multiplication.
$7x - 2 = 138$
2
Add 2 to both sides:
$7x - 2 + 2 = 138 + 2 \ \Rightarrow\ 7x = 140$
3
Divide both sides by 7:
$\frac{7x}{7} = \frac{140}{7} \ \Rightarrow\ x = 20$
4
Check: put x = 20 back into the equation.
$7\cdot20 - 2 = 140 - 2 = 138 \checkmark$

LaTeX source of the formulas on this page

\[ 7x - 2 = 138\ \Rightarrow\ x = 20 \]
\[ 7x - 2 = 138 \]
\[ 7x - 2 + 2 = 138 + 2 \ \Rightarrow\ 7x = 140 \]
\[ \frac{7x}{7} = \frac{140}{7} \ \Rightarrow\ x = 20 \]
\[ 7\cdot20 - 2 = 140 - 2 = 138 \checkmark \]

Trying values of x in 7x − 2 = 138

x	7x − 2	Equals 138?
18	124	no
19	131	no
20	138	yes
21	145	no
22	152	no

Questions

What is x in 7x − 2 = 138?

The solution of 7x − 2 = 138 is x = 20.

How do you solve 7x − 2 = 138?

Add 2 to both sides to get 7x = 140, then divide both sides by 7 to get x = 20.

How do I check the answer?

Replace x by 20: 7(20) − 2 = 138, which is 138.

Solve 7x − 2 = 138

How to work it out

Trying values of x in 7x − 2 = 138

Questions

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